1. Field of the Invention
The present invention relates to a laser beam irradiation apparatus, a method of sealing a substrate, and a method of manufacturing an organic light emitting display device.
2. Description of the Related Art
Recently, display devices are being replaced with portable, thin flat panel display devices. Among the flat panel display devices, electroluminescent display devices are self-emissive display devices which have a wide viewing angle and an excellent contrast ratio, and a high response speed, and thus are regarded as next-generation display devices. Also, an organic light emitting display device including an emission layer formed of an organic material has excellent luminosity, driving voltage, and response speed characteristics compared to inorganic light emitting display devices, and may realize multiple colors.
Organic light emitting display devices have a structure in which at least one organic layer including an emission layer is interposed between two electrodes.
When water or oxygen from the outside penetrates through the organic light emitting display device, an electrode material may be oxidized or exfoliation may occur, and this may reduce the lifespan and light emitting efficiency of the organic light emitting device, and light emitting colors may be deteriorated.
Accordingly, when manufacturing an organic light emitting display device, an organic light emitting device is usually sealed so as to isolate the organic light emitting device from the outside and so that water does not penetrate therein. Examples of the sealing process include a method in which an inorganic thin film and an organic polymer such as polyester (PET) are laminated on a second electrode of an organic light emitting display device, and a method in which an absorbent is formed in an encapsulation substrate and nitrogen gas is filled in the encapsulation substrate, and then a boundary of the encapsulation substrate is sealed using a sealant such as epoxy.
However, it is impossible to completely block such elements as water or oxygen penetrating from the outside, which destroy the organic light emitting device which is sealed using the above methods, and thus the methods cannot be applied to organic light emitting display devices which are particularly vulnerable to water, and a process for realizing the methods is also complicated. In order to solve these problems, a method in which frit is used as a sealant to improve adhesive properties between a substrate of the organic light emitting device and an encapsulation substrate has been designed.
By sealing an organic light emitting display device by coating frit on a glass substrate, the substrate of the organic light emitting device and the encapsulation substrate are completely sealed, thereby effectively protecting the organic light emitting display device.
A substrate is sealed using frit by coating the frit on a sealing unit of each of the organic light emitting display devices, and irradiating a laser beam onto a sealing unit of each of the organic light emitting display devices by moving a laser beam irradiation apparatus to irradiate the laser beam onto the sealing unit, thereby hardening the frit and sealing the substrate.